Semiconductor laser device

Abstract

A semiconductor laser device provided with a lower cladding layer, an active layer and an upper first cladding layer stacked in this order on a compound semiconductor substrate, a ridge-shaped upper second cladding layer provided on the upper first cladding layer, a light confining layer provided on both sides of the upper second cladding layer, and a contact layer provided on the upper second cladding layer. A current non-injection region having no contact layer is provided only on the laser emitting end face side. Although another current non-injection region may be also provided on the reflective end face side, the length of the current non-injection region on the reflective end face side is set to be shorter than that on the laser emitting end face side.

What is claimed is:  
     
       1. A semiconductor laser device, comprising 
       a lower cladding layer, an active layer and an upper first cladding layer stacked in this order on a compound semiconductor substrate,  
       a ridge-shaped upper second cladding layer provided on the upper first cladding layer,  
       a light confining layer provided on both sides of the upper second cladding layer, and  
       a contact layer provided on the upper second cladding layer,  
       wherein the device has a laser emitting end face and a reflective end face at both ends thereof with respect to a longitudinal direction of the ridge-shaped upper second cladding layer, and two current non-injection regions each having no contact layer are provided respectively in the vicinity of both of the laser emitting end face and the reflective end face, and  
       wherein a current non-injection length, which is a length of the current non-injection region along the longitudinal direction of the upper second cladding layer, is longer on the laser emitting end face side than on the reflective end face side.  
     
     
       2. A semiconductor laser device as claimed in  claim 1 , wherein 
       the current non-injection length on the laser emitting end face side is equal to or more than two times the current non-injection length on the reflective end face side.  
     
     
       3. A semiconductor laser device as claimed in  claim 1 , wherein 
       the compound semiconductor substrate is a GaAs compound semiconductor substrate;  
       the lower cladding layer is an Al x1 Ga (1-x1) As layer;  
       the active layer is a single layer of Al y11 Ga (1-y11) As, a composite layer formed of Al y11 Ga (1-y11) As and Al y12 Ga (1-y12) As layers, or a composite layer formed of Al y1 Ga (1-y1) As and GaAs layers;  
       the upper first cladding layer is an Al x2 Ga (1-x2) As layer;  
       the ridge-shaped upper second cladding layer is an Al x3 Ga (1-x3) As layer;  
       the light confining layer is an Al y2 Ga (1-y2) As layer; and  
       the contact layer is a GaAs layer.